In this project, we will conduct a systematic analysis of candidate genes for PCOS, testing for relevant differences between patients and unaffected controls at the level of both the DNA sequence and gene expression. Building on our previous findings of linkage in the region of the insulin receptor gene (INSR), our first goal will be to find and characterize the responsible gene or genetic element in this region. Accordingly, in Specific Aim 1, we will test for linkage disequilibrium with every known or suspected gene in the region. In Specific Aim 2, we will examine all genes from the region for transcripts in relevant tissues, and test for differences in mRNA abundance between PCOS patients and unaffected women. Additional family material will be obtained from, and characterized in, Project I (Dr. Dunaif); RNA and expression studies will be in collaboration with Dr. Strauss (Project III). In Specific Aim 3, we will also test a collection of other candidate genes, again carrying out investigations at both the DNA and expression levels. For about 35 genes we consider high-priority, we will test directly for linkage and linkage disequilibrium, using affected sib pair and TDT methods. Using cDNA microarrays, we will also test these genes and several hundred others for differential expression in available tissues from PCOS patients. For the family studies, we will benefit from access to samples from Amish families (see Specific Aim 4). All our investigations are integrated with those of the other projects. We expect that we will identify and characterize the genetic element in the INSR region that contributes to PCOS, and will identify other genes in the genome that contribute to making PCOS a "complex genetic disease."